1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2016 Facebook
3 */
4 #include <linux/bpf.h>
5 #include <linux/jhash.h>
6 #include <linux/filter.h>
7 #include <linux/kernel.h>
8 #include <linux/stacktrace.h>
9 #include <linux/perf_event.h>
10 #include <linux/btf_ids.h>
11 #include <linux/buildid.h>
12 #include "percpu_freelist.h"
13 #include "mmap_unlock_work.h"
14
15 #define STACK_CREATE_FLAG_MASK \
16 (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY | \
17 BPF_F_STACK_BUILD_ID)
18
19 struct stack_map_bucket {
20 struct pcpu_freelist_node fnode;
21 u32 hash;
22 u32 nr;
23 u64 data[];
24 };
25
26 struct bpf_stack_map {
27 struct bpf_map map;
28 void *elems;
29 struct pcpu_freelist freelist;
30 u32 n_buckets;
31 struct stack_map_bucket *buckets[];
32 };
33
stack_map_use_build_id(struct bpf_map * map)34 static inline bool stack_map_use_build_id(struct bpf_map *map)
35 {
36 return (map->map_flags & BPF_F_STACK_BUILD_ID);
37 }
38
stack_map_data_size(struct bpf_map * map)39 static inline int stack_map_data_size(struct bpf_map *map)
40 {
41 return stack_map_use_build_id(map) ?
42 sizeof(struct bpf_stack_build_id) : sizeof(u64);
43 }
44
prealloc_elems_and_freelist(struct bpf_stack_map * smap)45 static int prealloc_elems_and_freelist(struct bpf_stack_map *smap)
46 {
47 u64 elem_size = sizeof(struct stack_map_bucket) +
48 (u64)smap->map.value_size;
49 int err;
50
51 smap->elems = bpf_map_area_alloc(elem_size * smap->map.max_entries,
52 smap->map.numa_node);
53 if (!smap->elems)
54 return -ENOMEM;
55
56 err = pcpu_freelist_init(&smap->freelist);
57 if (err)
58 goto free_elems;
59
60 pcpu_freelist_populate(&smap->freelist, smap->elems, elem_size,
61 smap->map.max_entries);
62 return 0;
63
64 free_elems:
65 bpf_map_area_free(smap->elems);
66 return err;
67 }
68
69 /* Called from syscall */
stack_map_alloc(union bpf_attr * attr)70 static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
71 {
72 u32 value_size = attr->value_size;
73 struct bpf_stack_map *smap;
74 u64 cost, n_buckets;
75 int err;
76
77 if (attr->map_flags & ~STACK_CREATE_FLAG_MASK)
78 return ERR_PTR(-EINVAL);
79
80 /* check sanity of attributes */
81 if (attr->max_entries == 0 || attr->key_size != 4 ||
82 value_size < 8 || value_size % 8)
83 return ERR_PTR(-EINVAL);
84
85 BUILD_BUG_ON(sizeof(struct bpf_stack_build_id) % sizeof(u64));
86 if (attr->map_flags & BPF_F_STACK_BUILD_ID) {
87 if (value_size % sizeof(struct bpf_stack_build_id) ||
88 value_size / sizeof(struct bpf_stack_build_id)
89 > sysctl_perf_event_max_stack)
90 return ERR_PTR(-EINVAL);
91 } else if (value_size / 8 > sysctl_perf_event_max_stack)
92 return ERR_PTR(-EINVAL);
93
94 /* hash table size must be power of 2 */
95 n_buckets = roundup_pow_of_two(attr->max_entries);
96 if (!n_buckets)
97 return ERR_PTR(-E2BIG);
98
99 cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap);
100 smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr));
101 if (!smap)
102 return ERR_PTR(-ENOMEM);
103
104 bpf_map_init_from_attr(&smap->map, attr);
105 smap->n_buckets = n_buckets;
106
107 err = get_callchain_buffers(sysctl_perf_event_max_stack);
108 if (err)
109 goto free_smap;
110
111 err = prealloc_elems_and_freelist(smap);
112 if (err)
113 goto put_buffers;
114
115 return &smap->map;
116
117 put_buffers:
118 put_callchain_buffers();
119 free_smap:
120 bpf_map_area_free(smap);
121 return ERR_PTR(err);
122 }
123
stack_map_get_build_id_offset(struct bpf_stack_build_id * id_offs,u64 * ips,u32 trace_nr,bool user)124 static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
125 u64 *ips, u32 trace_nr, bool user)
126 {
127 int i;
128 struct mmap_unlock_irq_work *work = NULL;
129 bool irq_work_busy = bpf_mmap_unlock_get_irq_work(&work);
130 struct vm_area_struct *vma, *prev_vma = NULL;
131 const char *prev_build_id;
132
133 /* If the irq_work is in use, fall back to report ips. Same
134 * fallback is used for kernel stack (!user) on a stackmap with
135 * build_id.
136 */
137 if (!user || !current || !current->mm || irq_work_busy ||
138 !mmap_read_trylock(current->mm)) {
139 /* cannot access current->mm, fall back to ips */
140 for (i = 0; i < trace_nr; i++) {
141 id_offs[i].status = BPF_STACK_BUILD_ID_IP;
142 id_offs[i].ip = ips[i];
143 memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX);
144 }
145 return;
146 }
147
148 for (i = 0; i < trace_nr; i++) {
149 if (range_in_vma(prev_vma, ips[i], ips[i])) {
150 vma = prev_vma;
151 memcpy(id_offs[i].build_id, prev_build_id,
152 BUILD_ID_SIZE_MAX);
153 goto build_id_valid;
154 }
155 vma = find_vma(current->mm, ips[i]);
156 if (!vma || build_id_parse(vma, id_offs[i].build_id, NULL)) {
157 /* per entry fall back to ips */
158 id_offs[i].status = BPF_STACK_BUILD_ID_IP;
159 id_offs[i].ip = ips[i];
160 memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX);
161 continue;
162 }
163 build_id_valid:
164 id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i]
165 - vma->vm_start;
166 id_offs[i].status = BPF_STACK_BUILD_ID_VALID;
167 prev_vma = vma;
168 prev_build_id = id_offs[i].build_id;
169 }
170 bpf_mmap_unlock_mm(work, current->mm);
171 }
172
173 static struct perf_callchain_entry *
get_callchain_entry_for_task(struct task_struct * task,u32 max_depth)174 get_callchain_entry_for_task(struct task_struct *task, u32 max_depth)
175 {
176 #ifdef CONFIG_STACKTRACE
177 struct perf_callchain_entry *entry;
178 int rctx;
179
180 entry = get_callchain_entry(&rctx);
181
182 if (!entry)
183 return NULL;
184
185 entry->nr = stack_trace_save_tsk(task, (unsigned long *)entry->ip,
186 max_depth, 0);
187
188 /* stack_trace_save_tsk() works on unsigned long array, while
189 * perf_callchain_entry uses u64 array. For 32-bit systems, it is
190 * necessary to fix this mismatch.
191 */
192 if (__BITS_PER_LONG != 64) {
193 unsigned long *from = (unsigned long *) entry->ip;
194 u64 *to = entry->ip;
195 int i;
196
197 /* copy data from the end to avoid using extra buffer */
198 for (i = entry->nr - 1; i >= 0; i--)
199 to[i] = (u64)(from[i]);
200 }
201
202 put_callchain_entry(rctx);
203
204 return entry;
205 #else /* CONFIG_STACKTRACE */
206 return NULL;
207 #endif
208 }
209
__bpf_get_stackid(struct bpf_map * map,struct perf_callchain_entry * trace,u64 flags)210 static long __bpf_get_stackid(struct bpf_map *map,
211 struct perf_callchain_entry *trace, u64 flags)
212 {
213 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
214 struct stack_map_bucket *bucket, *new_bucket, *old_bucket;
215 u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
216 u32 hash, id, trace_nr, trace_len;
217 bool user = flags & BPF_F_USER_STACK;
218 u64 *ips;
219 bool hash_matches;
220
221 if (trace->nr <= skip)
222 /* skipping more than usable stack trace */
223 return -EFAULT;
224
225 trace_nr = trace->nr - skip;
226 trace_len = trace_nr * sizeof(u64);
227 ips = trace->ip + skip;
228 hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0);
229 id = hash & (smap->n_buckets - 1);
230 bucket = READ_ONCE(smap->buckets[id]);
231
232 hash_matches = bucket && bucket->hash == hash;
233 /* fast cmp */
234 if (hash_matches && flags & BPF_F_FAST_STACK_CMP)
235 return id;
236
237 if (stack_map_use_build_id(map)) {
238 /* for build_id+offset, pop a bucket before slow cmp */
239 new_bucket = (struct stack_map_bucket *)
240 pcpu_freelist_pop(&smap->freelist);
241 if (unlikely(!new_bucket))
242 return -ENOMEM;
243 new_bucket->nr = trace_nr;
244 stack_map_get_build_id_offset(
245 (struct bpf_stack_build_id *)new_bucket->data,
246 ips, trace_nr, user);
247 trace_len = trace_nr * sizeof(struct bpf_stack_build_id);
248 if (hash_matches && bucket->nr == trace_nr &&
249 memcmp(bucket->data, new_bucket->data, trace_len) == 0) {
250 pcpu_freelist_push(&smap->freelist, &new_bucket->fnode);
251 return id;
252 }
253 if (bucket && !(flags & BPF_F_REUSE_STACKID)) {
254 pcpu_freelist_push(&smap->freelist, &new_bucket->fnode);
255 return -EEXIST;
256 }
257 } else {
258 if (hash_matches && bucket->nr == trace_nr &&
259 memcmp(bucket->data, ips, trace_len) == 0)
260 return id;
261 if (bucket && !(flags & BPF_F_REUSE_STACKID))
262 return -EEXIST;
263
264 new_bucket = (struct stack_map_bucket *)
265 pcpu_freelist_pop(&smap->freelist);
266 if (unlikely(!new_bucket))
267 return -ENOMEM;
268 memcpy(new_bucket->data, ips, trace_len);
269 }
270
271 new_bucket->hash = hash;
272 new_bucket->nr = trace_nr;
273
274 old_bucket = xchg(&smap->buckets[id], new_bucket);
275 if (old_bucket)
276 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
277 return id;
278 }
279
BPF_CALL_3(bpf_get_stackid,struct pt_regs *,regs,struct bpf_map *,map,u64,flags)280 BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map,
281 u64, flags)
282 {
283 u32 max_depth = map->value_size / stack_map_data_size(map);
284 u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
285 bool user = flags & BPF_F_USER_STACK;
286 struct perf_callchain_entry *trace;
287 bool kernel = !user;
288
289 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
290 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
291 return -EINVAL;
292
293 max_depth += skip;
294 if (max_depth > sysctl_perf_event_max_stack)
295 max_depth = sysctl_perf_event_max_stack;
296
297 trace = get_perf_callchain(regs, 0, kernel, user, max_depth,
298 false, false);
299
300 if (unlikely(!trace))
301 /* couldn't fetch the stack trace */
302 return -EFAULT;
303
304 return __bpf_get_stackid(map, trace, flags);
305 }
306
307 const struct bpf_func_proto bpf_get_stackid_proto = {
308 .func = bpf_get_stackid,
309 .gpl_only = true,
310 .ret_type = RET_INTEGER,
311 .arg1_type = ARG_PTR_TO_CTX,
312 .arg2_type = ARG_CONST_MAP_PTR,
313 .arg3_type = ARG_ANYTHING,
314 };
315
count_kernel_ip(struct perf_callchain_entry * trace)316 static __u64 count_kernel_ip(struct perf_callchain_entry *trace)
317 {
318 __u64 nr_kernel = 0;
319
320 while (nr_kernel < trace->nr) {
321 if (trace->ip[nr_kernel] == PERF_CONTEXT_USER)
322 break;
323 nr_kernel++;
324 }
325 return nr_kernel;
326 }
327
BPF_CALL_3(bpf_get_stackid_pe,struct bpf_perf_event_data_kern *,ctx,struct bpf_map *,map,u64,flags)328 BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx,
329 struct bpf_map *, map, u64, flags)
330 {
331 struct perf_event *event = ctx->event;
332 struct perf_callchain_entry *trace;
333 bool kernel, user;
334 __u64 nr_kernel;
335 int ret;
336
337 /* perf_sample_data doesn't have callchain, use bpf_get_stackid */
338 if (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN))
339 return bpf_get_stackid((unsigned long)(ctx->regs),
340 (unsigned long) map, flags, 0, 0);
341
342 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
343 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
344 return -EINVAL;
345
346 user = flags & BPF_F_USER_STACK;
347 kernel = !user;
348
349 trace = ctx->data->callchain;
350 if (unlikely(!trace))
351 return -EFAULT;
352
353 nr_kernel = count_kernel_ip(trace);
354
355 if (kernel) {
356 __u64 nr = trace->nr;
357
358 trace->nr = nr_kernel;
359 ret = __bpf_get_stackid(map, trace, flags);
360
361 /* restore nr */
362 trace->nr = nr;
363 } else { /* user */
364 u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
365
366 skip += nr_kernel;
367 if (skip > BPF_F_SKIP_FIELD_MASK)
368 return -EFAULT;
369
370 flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
371 ret = __bpf_get_stackid(map, trace, flags);
372 }
373 return ret;
374 }
375
376 const struct bpf_func_proto bpf_get_stackid_proto_pe = {
377 .func = bpf_get_stackid_pe,
378 .gpl_only = false,
379 .ret_type = RET_INTEGER,
380 .arg1_type = ARG_PTR_TO_CTX,
381 .arg2_type = ARG_CONST_MAP_PTR,
382 .arg3_type = ARG_ANYTHING,
383 };
384
__bpf_get_stack(struct pt_regs * regs,struct task_struct * task,struct perf_callchain_entry * trace_in,void * buf,u32 size,u64 flags)385 static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
386 struct perf_callchain_entry *trace_in,
387 void *buf, u32 size, u64 flags)
388 {
389 u32 trace_nr, copy_len, elem_size, num_elem, max_depth;
390 bool user_build_id = flags & BPF_F_USER_BUILD_ID;
391 u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
392 bool user = flags & BPF_F_USER_STACK;
393 struct perf_callchain_entry *trace;
394 bool kernel = !user;
395 int err = -EINVAL;
396 u64 *ips;
397
398 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
399 BPF_F_USER_BUILD_ID)))
400 goto clear;
401 if (kernel && user_build_id)
402 goto clear;
403
404 elem_size = (user && user_build_id) ? sizeof(struct bpf_stack_build_id)
405 : sizeof(u64);
406 if (unlikely(size % elem_size))
407 goto clear;
408
409 /* cannot get valid user stack for task without user_mode regs */
410 if (task && user && !user_mode(regs))
411 goto err_fault;
412
413 num_elem = size / elem_size;
414 max_depth = num_elem + skip;
415 if (sysctl_perf_event_max_stack < max_depth)
416 max_depth = sysctl_perf_event_max_stack;
417
418 if (trace_in)
419 trace = trace_in;
420 else if (kernel && task)
421 trace = get_callchain_entry_for_task(task, max_depth);
422 else
423 trace = get_perf_callchain(regs, 0, kernel, user, max_depth,
424 false, false);
425 if (unlikely(!trace))
426 goto err_fault;
427
428 if (trace->nr < skip)
429 goto err_fault;
430
431 trace_nr = trace->nr - skip;
432 trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem;
433 copy_len = trace_nr * elem_size;
434
435 ips = trace->ip + skip;
436 if (user && user_build_id)
437 stack_map_get_build_id_offset(buf, ips, trace_nr, user);
438 else
439 memcpy(buf, ips, copy_len);
440
441 if (size > copy_len)
442 memset(buf + copy_len, 0, size - copy_len);
443 return copy_len;
444
445 err_fault:
446 err = -EFAULT;
447 clear:
448 memset(buf, 0, size);
449 return err;
450 }
451
BPF_CALL_4(bpf_get_stack,struct pt_regs *,regs,void *,buf,u32,size,u64,flags)452 BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size,
453 u64, flags)
454 {
455 return __bpf_get_stack(regs, NULL, NULL, buf, size, flags);
456 }
457
458 const struct bpf_func_proto bpf_get_stack_proto = {
459 .func = bpf_get_stack,
460 .gpl_only = true,
461 .ret_type = RET_INTEGER,
462 .arg1_type = ARG_PTR_TO_CTX,
463 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
464 .arg3_type = ARG_CONST_SIZE_OR_ZERO,
465 .arg4_type = ARG_ANYTHING,
466 };
467
BPF_CALL_4(bpf_get_task_stack,struct task_struct *,task,void *,buf,u32,size,u64,flags)468 BPF_CALL_4(bpf_get_task_stack, struct task_struct *, task, void *, buf,
469 u32, size, u64, flags)
470 {
471 struct pt_regs *regs;
472 long res = -EINVAL;
473
474 if (!try_get_task_stack(task))
475 return -EFAULT;
476
477 regs = task_pt_regs(task);
478 if (regs)
479 res = __bpf_get_stack(regs, task, NULL, buf, size, flags);
480 put_task_stack(task);
481
482 return res;
483 }
484
485 const struct bpf_func_proto bpf_get_task_stack_proto = {
486 .func = bpf_get_task_stack,
487 .gpl_only = false,
488 .ret_type = RET_INTEGER,
489 .arg1_type = ARG_PTR_TO_BTF_ID,
490 .arg1_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
491 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
492 .arg3_type = ARG_CONST_SIZE_OR_ZERO,
493 .arg4_type = ARG_ANYTHING,
494 };
495
BPF_CALL_4(bpf_get_stack_pe,struct bpf_perf_event_data_kern *,ctx,void *,buf,u32,size,u64,flags)496 BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx,
497 void *, buf, u32, size, u64, flags)
498 {
499 struct pt_regs *regs = (struct pt_regs *)(ctx->regs);
500 struct perf_event *event = ctx->event;
501 struct perf_callchain_entry *trace;
502 bool kernel, user;
503 int err = -EINVAL;
504 __u64 nr_kernel;
505
506 if (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN))
507 return __bpf_get_stack(regs, NULL, NULL, buf, size, flags);
508
509 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
510 BPF_F_USER_BUILD_ID)))
511 goto clear;
512
513 user = flags & BPF_F_USER_STACK;
514 kernel = !user;
515
516 err = -EFAULT;
517 trace = ctx->data->callchain;
518 if (unlikely(!trace))
519 goto clear;
520
521 nr_kernel = count_kernel_ip(trace);
522
523 if (kernel) {
524 __u64 nr = trace->nr;
525
526 trace->nr = nr_kernel;
527 err = __bpf_get_stack(regs, NULL, trace, buf, size, flags);
528
529 /* restore nr */
530 trace->nr = nr;
531 } else { /* user */
532 u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
533
534 skip += nr_kernel;
535 if (skip > BPF_F_SKIP_FIELD_MASK)
536 goto clear;
537
538 flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
539 err = __bpf_get_stack(regs, NULL, trace, buf, size, flags);
540 }
541 return err;
542
543 clear:
544 memset(buf, 0, size);
545 return err;
546
547 }
548
549 const struct bpf_func_proto bpf_get_stack_proto_pe = {
550 .func = bpf_get_stack_pe,
551 .gpl_only = true,
552 .ret_type = RET_INTEGER,
553 .arg1_type = ARG_PTR_TO_CTX,
554 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
555 .arg3_type = ARG_CONST_SIZE_OR_ZERO,
556 .arg4_type = ARG_ANYTHING,
557 };
558
559 /* Called from eBPF program */
stack_map_lookup_elem(struct bpf_map * map,void * key)560 static void *stack_map_lookup_elem(struct bpf_map *map, void *key)
561 {
562 return ERR_PTR(-EOPNOTSUPP);
563 }
564
565 /* Called from syscall */
bpf_stackmap_copy(struct bpf_map * map,void * key,void * value)566 int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value)
567 {
568 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
569 struct stack_map_bucket *bucket, *old_bucket;
570 u32 id = *(u32 *)key, trace_len;
571
572 if (unlikely(id >= smap->n_buckets))
573 return -ENOENT;
574
575 bucket = xchg(&smap->buckets[id], NULL);
576 if (!bucket)
577 return -ENOENT;
578
579 trace_len = bucket->nr * stack_map_data_size(map);
580 memcpy(value, bucket->data, trace_len);
581 memset(value + trace_len, 0, map->value_size - trace_len);
582
583 old_bucket = xchg(&smap->buckets[id], bucket);
584 if (old_bucket)
585 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
586 return 0;
587 }
588
stack_map_get_next_key(struct bpf_map * map,void * key,void * next_key)589 static int stack_map_get_next_key(struct bpf_map *map, void *key,
590 void *next_key)
591 {
592 struct bpf_stack_map *smap = container_of(map,
593 struct bpf_stack_map, map);
594 u32 id;
595
596 WARN_ON_ONCE(!rcu_read_lock_held());
597
598 if (!key) {
599 id = 0;
600 } else {
601 id = *(u32 *)key;
602 if (id >= smap->n_buckets || !smap->buckets[id])
603 id = 0;
604 else
605 id++;
606 }
607
608 while (id < smap->n_buckets && !smap->buckets[id])
609 id++;
610
611 if (id >= smap->n_buckets)
612 return -ENOENT;
613
614 *(u32 *)next_key = id;
615 return 0;
616 }
617
stack_map_update_elem(struct bpf_map * map,void * key,void * value,u64 map_flags)618 static long stack_map_update_elem(struct bpf_map *map, void *key, void *value,
619 u64 map_flags)
620 {
621 return -EINVAL;
622 }
623
624 /* Called from syscall or from eBPF program */
stack_map_delete_elem(struct bpf_map * map,void * key)625 static long stack_map_delete_elem(struct bpf_map *map, void *key)
626 {
627 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
628 struct stack_map_bucket *old_bucket;
629 u32 id = *(u32 *)key;
630
631 if (unlikely(id >= smap->n_buckets))
632 return -E2BIG;
633
634 old_bucket = xchg(&smap->buckets[id], NULL);
635 if (old_bucket) {
636 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
637 return 0;
638 } else {
639 return -ENOENT;
640 }
641 }
642
643 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
stack_map_free(struct bpf_map * map)644 static void stack_map_free(struct bpf_map *map)
645 {
646 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
647
648 bpf_map_area_free(smap->elems);
649 pcpu_freelist_destroy(&smap->freelist);
650 bpf_map_area_free(smap);
651 put_callchain_buffers();
652 }
653
stack_map_mem_usage(const struct bpf_map * map)654 static u64 stack_map_mem_usage(const struct bpf_map *map)
655 {
656 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
657 u64 value_size = map->value_size;
658 u64 n_buckets = smap->n_buckets;
659 u64 enties = map->max_entries;
660 u64 usage = sizeof(*smap);
661
662 usage += n_buckets * sizeof(struct stack_map_bucket *);
663 usage += enties * (sizeof(struct stack_map_bucket) + value_size);
664 return usage;
665 }
666
667 BTF_ID_LIST_SINGLE(stack_trace_map_btf_ids, struct, bpf_stack_map)
668 const struct bpf_map_ops stack_trace_map_ops = {
669 .map_meta_equal = bpf_map_meta_equal,
670 .map_alloc = stack_map_alloc,
671 .map_free = stack_map_free,
672 .map_get_next_key = stack_map_get_next_key,
673 .map_lookup_elem = stack_map_lookup_elem,
674 .map_update_elem = stack_map_update_elem,
675 .map_delete_elem = stack_map_delete_elem,
676 .map_check_btf = map_check_no_btf,
677 .map_mem_usage = stack_map_mem_usage,
678 .map_btf_id = &stack_trace_map_btf_ids[0],
679 };
680
